001/*******************************************************************************
002 * This software is provided as a supplement to the authors' textbooks on digital
003 * image processing published by Springer-Verlag in various languages and editions.
004 * Permission to use and distribute this software is granted under the BSD 2-Clause
005 * "Simplified" License (see http://opensource.org/licenses/BSD-2-Clause).
006 * Copyright (c) 2006-2023 Wilhelm Burger, Mark J. Burge. All rights reserved.
007 * Visit https://imagingbook.com for additional details.
008 ******************************************************************************/
009package Ch21_Geometric_Operations;
010
011import ij.ImagePlus;
012import ij.plugin.filter.PlugInFilter;
013import ij.process.ImageProcessor;
014import imagingbook.common.geometry.basic.Pnt2d;
015import imagingbook.common.geometry.mappings.Mapping2D;
016import imagingbook.common.ij.DialogUtils;
017import imagingbook.common.ij.IjUtils;
018import imagingbook.common.image.ImageMapper;
019import imagingbook.common.image.OutOfBoundsStrategy;
020import imagingbook.common.image.interpolation.InterpolationMethod;
021import imagingbook.core.jdoc.JavaDocHelp;
022import imagingbook.sampleimages.GeneralSampleImage;
023
024/**
025 * <p>
026 * ImageJ plugin, applies a non-linear "twirl" transformation to the current image. See Sec. 21.1.7 (Exercise 21.9 and
027 * Fig. 21.18) of [1] for details. Optionally opens a sample image if no image is currently open.
028 * </p>
029 * <p>
030 * [1] W. Burger, M.J. Burge, <em>Digital Image Processing &ndash; An Algorithmic Introduction</em>, 3rd ed, Springer
031 * (2022).
032 * </p>
033 *
034 * @author WB
035 * @version 2022/11/28
036 * @see ImageMapper
037 * @see Mapping2D
038 */
039public class Map_Nonlinear_Twirl implements PlugInFilter, JavaDocHelp {
040        
041        private static double alpha = Math.toRadians(43.0);     // angle (43 degrees)
042
043        /**
044         * Constructor, asks to open a predefined sample image if no other image
045         * is currently open.
046         */
047        public Map_Nonlinear_Twirl() {
048                if (IjUtils.noCurrentImage()) {
049                        DialogUtils.askForSampleImage(GeneralSampleImage.Flower);
050                }
051        }
052        
053        @Override
054        public int setup(String arg, ImagePlus imp) {
055                return DOES_ALL;
056        }
057
058        @Override
059        public void run(ImageProcessor ip) {
060                final double xc = 0.5 * ip.getWidth();
061                final double yc = 0.5 * ip.getHeight();
062                final double rmax = Math.sqrt(xc * xc + yc * yc);
063                
064                Mapping2D imap = new Mapping2D() {      // inverse mapping (target to source)
065                        @Override
066                        public Pnt2d applyTo(Pnt2d uv) {
067                                double dx = uv.getX() - xc;
068                                double dy = uv.getY() - yc;
069                                double r = Math.sqrt(dx * dx + dy * dy);
070                                if (r < rmax) {
071                                        double beta = Math.atan2(dy, dx) + alpha * (rmax - r) / rmax;
072                                        double x = xc + r * Math.cos(beta);
073                                        double y = yc + r * Math.sin(beta);
074                                        return Pnt2d.from(x, y);
075                                }
076                                else {
077                                        return uv;      // return the original point
078                                }
079                        }
080                };
081                
082                new ImageMapper(imap, OutOfBoundsStrategy.ZeroValues, InterpolationMethod.Bicubic).map(ip);
083        }
084        
085}